It is generally believed that trees are able to obtain all their nutrients and water from the soil. While this is possible under ideal conditions, very often growing conditions are not ideal, which leads to poor growth. To enhance their chances for survival, the roots of trees and soil organisms have developed a symbiotic existence. The trees manufacture by photosynthesis and donate energy, in the form of sugars, to the microorganisms, which then employ the sugars to decompose organic matter and rocks to release nutrients. Such decomposition results in more nutrients than the microorganisms need and the excess is transferred to feeder roots of the tree. In this way, difficult to obtain nutrients, such as phosphorus and micronutrients, are obtained by the roots.
Under normal circumstances, this symbiotic system provides enough minerals for trees to grow and enough energy for the microorganisms to survive. However, any occurrence which diminishes the rate of photosynthesis, results in a decline of tree growth and microorganism population. For example, during the last century, industry has generated a variety of toxic chemicals which have been placed in the atmosphere.
One of the worst pollutants from the perspective of a tree is ground level ozone. This gas enters the plant, penetrates cell walls and damages cell membranes. To prevent loss of cell content, the cell tries to repair itself and, in so doing, cuts back on photosynthesis and uses energy, as well as activating many enzymes which results in an increased need for nutrients. The ozone also interferes with the transfer of sugar from leaves to roots, which leads to a low energy level for the microorganisms and poor uptake of nutrients by the feeder roots.
As the microorganism population declines as a result of a decrease in available energy, the roots of the tree cannot feed the whole canopy of the tree, resulting in the initiation of die-back. Prior to the inventors discovery thereof, it is thought that the mechanism of die-back of trees as outlined above was not understood, although several theories had been proposed. No known chemical fertilizer is able to prevent or cure the problem.